Generally, a washing machine is an electric appliance which washes clothes, beddings and cloth items (hereinafter, referenced to as ‘laundry) by using water, detergent and a mechanical action via washing, rinsing and spinning cycles, to remove contaminants.
The washing machine is categorized into an agitator type washing machine, a pulsator type washing machine and a drum type washing machine.
In the agitator type washing machine, an agitator vertically mounted in a center of a tub is rotated in a right and left direction to perform washing. In the pulsator type washing machine, a disc-shaped pulsator mounted below a tub is rotated in a right and left direction and washing is performed by a frictional force generated between water currents and laundry loaded therein. In the drum type washing machine, water, detergent and laundry are loaded into a drum and the drum is rotated to wash the laundry.
The drum type washing machine includes a cabinet configured to define a profile of the washing machine, a tub mounted in the cabinet to hold wash water, a drum mounted in the tub to receive laundry therein, a motor mounted to a rear surface of the tub to rotate the drum and a driving shaft connected to the motor and a rear surface of the drum, passing through the tub. A lifter is installed in the drum to lift the laundry when the drum is rotating.
While the drum is rotated, laundry is lifted by the lifter installed in such the drum type washing machine and the laundry is rotated in close contact with an inner circumferential surface of the drum to be lifted and dropped (hereinafter, ‘tumbled’), to perform washing. Demands for various washing methods to improve a washing ability have been increasing, rather than such a tumbling motion.